Allow selective removal of Usage Table Entries by PST

This is a merge of http://go/wvgerrit/13693 in the Widevine
repository.

This adds level 3 and mock implementation and unit tests for the
OEMCrypto function OEMCrypto_ForceDeleteUsageEntry.  It also plumbs
this function up into CdmEngine, CdmSession, and CryptoSession so that
deleting all usage information for a given app id will now delete the
entries in OEMCrypto, too.

b/18194071

Change-Id: Iaea4034a507b323878657215784edfe95876386a

libwvdrmengine/cdm/core/include/crypto_session.h

@@ -96,6 +96,14 @@ class CryptoSession {
   virtual CdmResponseType ReleaseUsageInformation(
       const std::string& message, const std::string& signature,
       const std::string& provider_session_token);
+  // Delete a usage information for a single token.  This does not require
+  // a signed message from the server.
+  virtual CdmResponseType DeleteUsageInformation(
+      const std::string& provider_session_token);
+  // Delete usage information for a list of tokens.  This does not require
+  // a signed message from the server.
+  virtual  CdmResponseType DeleteMultipleUsageInformation(
+      const std::vector<std::string>& provider_session_tokens);
   virtual CdmResponseType DeleteAllUsageReports();
   virtual bool IsAntiRollbackHwPresent();